The directed synthesis of cluster-compounds is a current problem in transition metal chemistry"'. For the subgroup VI metals (Mo and W) with d" configuration, cluster types are expected to be dumb-bell shaped (in the case where n= I), triangular ( n = 2), tetrahedral (n = 3) and octahedral (n = 4) (here n also indicates the number of metal-metal bonds originating from each metal atom). Recently, the first binary species with n = l , uiz [ M O~( S , )~]~-, has been isolated in the form of its ammonium salt [']. We now report the synthesis of the homologous cluster with n = 2 from a solution containing Mo". Hitherto, the transition metal sulfur clusters, as model compounds of bioinorganic interest, could only be obtained by unusual reactions from unusual reactants and often only in lowThe dark-red, crystalline compound (NH4)2[Mo3S(S2)6]. the same length [']. As expected, the Mo-Mo distances (2.67 A) are somewhat shorter in ( I ) and the coordination number of molybdenum is again 9[41.The Si-ligands favor high coordination numbers and are suitable for stabilizing metal clusters, since an optimum shielding of the metal atoms is achieved through the high coordination numbers arising due to the small MSz-angle. From the above mentioned scheme the existence of the homologouscould be predictedL6! Obviously the stability of these compounds is also connected with the occurrence of only tricoordinated sulfur in the central units ({ M o~S ( S Z )~} (in (1 )) and probably {Mo4S4}L6l (for the low reactivity cf. [31). Experimental30ml of saturated ammonium polysulfide is added to a reddish brown solution of 2.Og of (NH4)6M07024.4HZ0 and 1.5g of NHzOH.HCl in 30ml water. The resulting solution is warmed to 40-50°C for 1 h, then cooled to room temperature, filtered, and the filtrate heated at ca. 90°C for 3-4 h.Dark-red crystals of (1) Angew. Chem. 87, 363 (1975); Angew. Chem. Int. Ed.Engl. 14, 322 (1975). [4] Details of the X-ray structure analysis will be published later. The water content follows from elemental analysis and T G but could not be finally confirmed by structure analysis.[S] Because of thecoupling in the ring system thedesignation of the vibrations is only approximate.[6] The central unit has already been found in [(C5H5)MoSI4 (cf. [3]). Optically Active Polyvinyl Compounds with Chirality in the Main Chain[**]By Giinter W u g Karl Zabrocki, and Johann Hohn"]We recently described a method for the preparation of synthetic polymers having cavities containing functional groups in a definite steric arrangement[" ' I. Functionally substituted polymerizable vinyl compounds were bound to a suitable chiral template molecule and then copolymerized under stringent crosslinking conditions. After removal of the template from the polymer the latter contains microcavities, whose shape is largely determined by the shape of the template, and within which the functional groups are in a fixed stereochemistry corresponding to the structure of the template. Such polymers can be used for the resolution of racemates ['].In order to c...

Die in reiner Form isolierten Verbindungen Na4Ge2S6 · 14 H2O (I) und Na4Sn2S6 · 14 H2O (II) wurden durch eine vollständige Röntgenstrukturanalyse charakterisiert. Die in der Litreatur bisher beschriebenen „Trithiogermanate MI2GeS3”︁ und „Trithiostannate MI2SnS3”︁ erweisen sich danach als Verbindungen mit isolierten Ge2S4−6 ‐ bzw. Sn2S4−6 ‐Ionen, die aus zwei über eine Kante verknüpften Tetraedern bestehen. Hexathiodiegermant und ‐distanat bilden einen bisher nicht beobachteten Typ anorganischer Tetraderionen. I und II sind iostyp und kristallisieren triklin (P1) mit a = 9,978 (10,114), b = 7,202 (7,027), c = 9,601 (9,801) Å, α = 018,41 (108,29) β = 92,39 (92,18), γ = 91,69 (91,11)° Z = 1. In den Ge2S4−6(Sn2S4−6)‐Ionen sind die endständigen Ge–S(Sn–S)‐Bindungen mit 2,170 (2,332) Å deutlich kürzer als die Brückenbindungen des gespannten 4‐Ringes mit 2,272 (2,450) Å. Das umfangreiche OH…︁O‐ und OH…︁S‐Brückensystem der beiden Salzhydrate wurde vollständig analysiert.

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The first bidentate, peralkylated guanidine based ligand has been synthesized and its complexation chemistry examined by the preparation of three representative coordination compounds. The novel chelate ligand 1,3-bis(N,N,NЈ,NЈ-tetramethylguanidino)propane (btmgp, 1) has been synthesized by the reaction of N,N,NЈ,NЈtetramethylguanidine (TMG) with 1,3-dibromopropane and subsequent deprotonation of the resulting guanidinium salt with sodium ethoxide. The bifunctional N-donor compound was treated with copper() iodide, copper() chloride and iron() iodide in a 1 : 1 molar ratio to yield the corresponding electroneutral complexes [CuI(btmgp)] 2, [CuCl 2 (btmgp)] 3 and [FeI 2 (btmgp)] 4. The structures of the dihydrochloride of 1 (1b) and of the complexes 2-4 have been determined by X-ray crystallography. A comparison of the molecular structures (2-4) shows that, in each case, btmgp acts as a bidentate ligand which is able to stabilize not only trigonal-planar (2), but also (distorted) square-planar (3) and tetrahedral coordination environments (4).

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